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Evidence-Based Reviews

Dependence risk with chronic dextromethorphan abuse

‘Robo-ing’ patients may meet diagnostic criteria

Vol. 4, No. 2 / February 2005

Habitual users of dextromethorphan can develop symptoms that meet DSM-IV criteria for substance dependence. A common ingredient in nonprescription cough syrups, dextromethorphan is considered nonaddictive but is far from benign in excessive dosages.

To illustrate the risks of dextromethorphan abuse, this article:

  • presents the case of an adult with apparent dependence
  • provides evidence of psychiatric and medical consequences of chronic excessive use of this cough remedy
  • offers a glimpse at how dextromethorphan is described on the Internet, where information on its recreational use is readily available.1

Box 1

Dextromethorphan’s mechanism of action and metabolism

Dextromethorphan acts on the brain’s cough center, the medulla oblongata, raising the cough reflex threshold. It is well-absorbed by the GI tract, metabolized in the liver by the cytochrome P-450 2D6 isoenzyme, and excreted in the urine unchanged or as a demethylated metabolite.2,3

Interaction between dextromethorphan and MAOIs resulting in serotonergic syndrome has been well-documented.4

Dextromethorphan has a 15- to 30-minute onset of action and peaks in 2.5 hours. Duration of action is 3 to 6 hours.5 Though dextromethorphan is an opiate analog, it is regarded as having no analgesic or addictive properties.6 When taken in therapeutic dosages—one-sixth to one-third ounce of medication containing 15 to 30 mg dextromethorphan—it is considered highly effective and safe,1 with no analgesic, euphoric, or dependency-producing properties.3

Dextromethorphan has a wide margin of safety. Doses 100 times the recommended amount have not been fatal,1 although overdose deaths have occurred.3


Dextromethorphan is a antitussive (cough suppressant) developed in the 1950s as a nonopioid alternative to codeine. Considered safe and effective at therapeutic dosages (Box 1),1-6 it can cause dissociation and psychotic effects in overdose.

Dextromethorphan is an attractive drug of abuse because it:

  • produces the desired intoxicating effect
  • is inexpensive—usually less than $5 a bottle
  • is easy to purchase without prescription in >120 cough syrup preparations.7

On the other hand, dextromethorphan is not as accepted by drug users as are marijuana, alcohol, and cocaine. Our patients tell us:

  • persons who abuse cough syrup say it tastes terrible
  • the hallucinations and dissociation associated with dextromethorphan intoxication can be unpleasant, even frightening
  • cough syrup is seen as a drug for “losers.”

Those who use dextromethorphan chronically tend to do so in solitude, which suggests that many users may go unrecognized.


Mr. E, age 26, presented to our clinic for a court-ordered evaluation of substance abuse after his third drunken driving arrest. A college senior and father of three, he denied abusing nonprescription medications but volunteered that his alcohol consumption was “under control.” He said he continued to “drink on occasion,” including “less than three” glasses of wine the night of his arrest.

At the counselor’s recommendation, Mr. E underwent intensive outpatient counseling. He accepted that he had a genetic predisposition to addiction, gained insight into his alcohol abuse, and began a 12-step recovery program. The day he was to be discharged from treatment, however, Mr. E asked for a session with his counselor and revealed that he had been abusing “DXM” (dextromethorphan) in cough syrup for 11 years. He admitted drinking two 6- to 8-oz bottles of Robitussin-DM-brand cough syrup daily for the last 5 years, an activity he called “Robo-ing.”

He claimed to be a “highly revered teacher.” He said he “championed DXM use” and that “everyone looked up to” him because he had introduced “hundreds of people to the high.”

He had taught others to camouflage the cough syrup’s taste by chewing gum or gulping soft drinks. Maintaining a steady DXM level in the body “enhances” any other drug or alcohol use, he said. Mr. E described his DXM use fondly, though now with some fear.

Mr. E begged for help. Because of DXM use, his marriage was failing, he had been fired from his job, he was struggling to pay his legal fines, and he had spent time in jail. He feared he had damaged his brain and worried that his DXM use might have contributed to birth defects in two of his children.

Mr. E continued outpatient psychotherapy for 5 months to address his DXM use triggers—seeing cough syrup in stores, any alcohol use, and stress. He researched DXM addiction and was amazed to find no 12-step programs or information on DXM and birth defects.

We met with him 7 months after discharge. He reported that his marriage “has never been better,” and his children seemed to have no developmental delays. He was graduating from college and returning to his hometown to work.

Two years later, he is back in treatment for dextromethorphan abuse.


Mr. E believes he is dependent on dextromethorphan, and his behavior meets DSM-IV-TR criteria for dependence (Table):

  • His persistent development of a culture of dextromethorphan use consumes much of his time.
  • He neglects family and work responsibilities.
  • He has tried repeatedly to cut down and stop his cough syrup use.
  • His use continues despite marital, work, and legal consequences.
  • He can tolerate daily dextromethorphan doses that would not be possible for the naive user.
  • He experiences physical and psychological withdrawal when he stops using dextromethorphan.

Table 1

DSM-IV-TR criteria for substance dependence

A maladaptive pattern of substance use, leading to clinically significant impairment or distress, as manifested by three (or more) of the following, occurring at any time in the same 12-month period:

  1. Tolerance, as defined by either of the following:
  2. Withdrawal, as manifested by either of the following:
  3. The substance is often taken in larger amounts or over a longer period than was intended
  4. There is persistent desire or unsuccessful efforts to cut down or control substance use.
  5. A great deal of time is spent in activities necessary to obtain the substance (eg, visiting multiple doctors or driving long distances), use the substance (eg, chain smoking), or recover from its effects
  6. Important social, occupational, or recreational activities are given up because of substance use
  7. The substance use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substance.

Source: Adapted and reprinted with permission from the Diagnostic and Statistical Manual of Mental Disorders (4th ed, text revision). Copyright 2000. American Psychiatric Association.

Box 2

Warning to parents: Signs of child or adolescent dextromethorphan abuse

  • Cough syrup bottle in home’s medicine cabinet looks more empty than expected
  • Child is using the Internet to learn about or attempt to purchase products containing dextromethorphan
  • Cough syrups or other products containing dextromethorphan are found in child’s possession
  • Child denies using common street drugs or alcohol but displays an unexplained altered state (confusion, ataxia, dizziness, euphoria, or slowed mental processing) or nausea, vomiting, or dizziness (from dextromethorphan withdrawal)
  • Child hangs out with peers in drug stores or supermarkets
  • Using cough syrup to get high has become a fad in child’s school or peer group

He claims that about one-third of his peer group has tried dextromethorphan to get high, although he believes <1% are “addicted.” He describes “a pocket of users.” In his experience, long-term use is “unusual.” His return to dextromethorphan after an extended abstinence reinforces its dependence potential.


The prevalence of dextromethorphan abuse is unclear.8 Abuse has been reported in Sweden, Canada, Australia, Germany, and the United States.1 Sweden has allowed prescription-only sales as a deterrent to abuse since 1986.9

The literature and our experience in treating dextromethorphan abusers suggest that abuse often begins in late childhood or early adolescence but may continue as chronic behavior in adulthood.

Use by adolescents. Case reports note episodic or fad dextromethorphan use—usually by adolescents and young adults—that springs up in a region or within a group and then fades.8 An abuse epidemic by Utah adolescents in the 1980s led drug stores to voluntarily place dextromethorphan-containing products behind the pharmacy counter to monitor and deter purchases.10

In a study of 376 students in grades 4 through 12 in Albuquerque, New Mexico, many knew cough syrup could be used to “get high.” When shown a list of cough syrup brand names, they often could identify those containing dextromethorphan, including NyQuil, Robitussin-DM, and Vicks 44D. The rates at which the students knew these three common cough preparations could be abused were:

  • 46%, 25%, and 16%, respectively, for high school students
  • 20%, 10%, and 17% for middle schoolers.8

Because many youngsters know that dextromethorphan abuse can produce an altered state, clinicians need to educate parents to be alert for warning signs in their children (Box 2).

Use by adults. Substance abuse counselors at our agency all have worked with adults who use cough syrup for intoxication. Some adults say they use dextromethorphan to enjoy the high and others as an alternative to alcohol.


Many Internet sites carry information about dextromethorphan.11-13 Its altered state is called a plateau, and four plateaus have been described.

Lower plateaus are considered “recreational.”13 According to the National Institute on Drug Abuse (NIDA), users experience a sense of dissociation and distortion of time and space at doses of about 2 ounces of medication containing 15 to 30 mg of dextromethorphan.14

Users are said to try to attain plateaus 1 or 2 to enhance and enjoy their surroundings. They describe music as being richer, colors more intense, and conversation more meaningful. The experience is said to be similar to a marijuana high or alcohol intoxication.

Objects may appear disproportionately large or small. The normal rhythm of conversation may seem chopped into blocks of words, or words may echo. Users refer to this staccato or strobing quality of sound as “flanging.”13 The bodily experience has been described as dreamlike or as if standing on a wave.

The high at lower plateaus is generally described as a positive experience. However, some describe it as bizarre, weird, and disturbing. It can create panic, nausea, and vomiting.

Upper plateaus. Users consider plateaus 3 and 4 as less recreational and more “spiritual and introspective.”15 Substantial dissociation and hallucinations can occur with “heavy stoning”—which the NIDA defines as using 10 ounces or more of medication containing 15 to 30 mg of dextromethorphan.14 Web sites warn users not to try to attain the upper plateaus unless prepared to “sit it out” or be accompanied by a sober “sitter” to talk the user through a bad trip or get help if needed.13


The upper plateaus of dextromethorphan abuse are described as “intense.” Users report hallucinations, time and space distortions, and out-of-body sensations. Some have reported contacting alien beings or spirits. Although some users report the higher plateaus as pleasant, others report them as “terrifying.”

Upper-level trips can result in panic attacks and psychosis. Case reports have documented dextromethorphan doses that resulted in emergency room visits for psychotic states. For example:

  • an adult was treated in the emergency room for psychosis after consuming an estimated 711 mg of dextromethorphan from cough syrup16
  • a 23-year-old was treated for agitation and hallucinations in an emergency room after consuming approximately 2,160 mg of dextromethorphan.17

Memory loss, disorganization, and altered consciousness appear to be temporary and resolve with discontinued use. Few persons experiment repeatedly with attaining the upper plateaus, an activity often followed by nausea, vomiting, and a hangover that lasts for days.

Research is lacking on long-term effects of regular dextromethorphan use. One study reported birth defects in chick embryos exposed to dextromethorphan.18

Fatalities. Dextromethorphan-related deaths have been documented.19 Causes of death include respiratory arrest, seizure, aspiration, and drug-drug interactions.20 Because dextromethorphan is usually not taken in pure form, effects of other drugs in cough syrup—such as bromide or chlorpheniramine—may contribute to the risk of side effects or death.21

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